Today, with the rapid development of mobile technology, a large number of multimedia services emerge. In some application services, multiple users can simultaneously receive the same data, such as video on demand, television broadcast, video conference, mobile TV, etc. In order to efficiently utilize mobile network resources, WCDMA/GSM global standardization organization 3GPP puts forward a Multimedia Broadcast Multicast Service (MBMS)/an evolved Multimedia Broadcast Multicast Service (e-MBMS). The MBMS/e-MBMS refers to a point-to-multipoint service in which data are transmitted from a single data source to multiple users to share network resources. The MBMS/e-MBMS defined by 3GPP enables not only multicast and broadcast of plain text, low rate messages, but also multicast and broadcast of high-rate multimedia services, which undoubtedly conforms to the development trend of future mobile data.
In addition, statistical multiplexing technology is widely used in a multi-stream transmission system. Multiplexing parallel streams results in considerable a multiplexing gain. The multiplexing gain is achieved by statistics of services, i.e. when one of the streams needs more bandwidths, some other streams will statistically undergo a low bit rate state. Statistical multiplexing is applicable to a broadcasting system because a gain is achieved by utilizing application statistics characters rather than others like physical layer feedback. The multiplexing gain is quite considerable, e.g. it has been found that a gain of 30%-40% can be achieved in DVB-H.
Thus, it is necessary to perform statistical multiplexing in the MBMS/e-MBMS system to achieve higher efficiency of resource utilization.
The basic concept of performing statistical multiplexing of the services with the same Quality of Service Class Identifier (QCI) has been proposed.
FIG. 1 illustrates a schematic diagram of the existing evolved Multimedia Broadcast Multicast Service (e-MBMS) system for performing statistical multiplexing of services with the same QCI.
QCI comprises parameters such as bit rate, bit error rate, requirement on delay and priority level required by achieving the Quality of Service Level of services.
An evolved Broadcast Multicast Service Center (eBM-SC) achieves provision and management of the MBMS service. For a content provider, BM-SC is an entrance of the MBMS service content. For a bearer network, eBM-SC is in charge of authorizing and initiating e-MBMS services/and scheduling and transmitting e-MBMS service contents.
As shown in FIG. 1, eBM-SC firstly acquires statistical parameters of services with the same QCI, and determines a statistical multiplexing bundle and information of the statistical multiplexing bundle, wherein the information of the statistical multiplexing bundle may include: a list of services within the bundle represented for example by a list of a Temporal Mobile Group Identify (TMGI), the QCI requested by the statistical multiplexing bundle and the Aggregated Bundle Bit
Rate (ABBR) of the statistical multiplexing bundle. Then, eBM-SC informs an encoder of the ABBR so that the encoder can make joint encoding of multiple services in the aggregated bundle; the total code rate of data streams of multiple services can keep constant; and these services can rationally share the total code rate. The eBM-SC transmits the information of the statistical multiplexing bundle via a gateway to MBMS
Collaborative Entity (MCE) so that the MCE can perform resource allocation. On the allocated resources, via MAC multiplexing, eNodeB multiplexes IP packets to the same Transmission Block (TB) to multiplex the services to the same Multicast Channel (MCH).
FIG. 2 illustrates a schematic diagram of the existing method for performing statistical multiplexing of the services with the same QCI.
For a case including service stream 1 (QCI1), service stream 2 (QCI1), service stream 3 (QCI2), service stream 4 (QCI3) and service stream 5 (QCI4), eBM-SC firstly determines statistical multiplexing bundle 1 {service stream 1 (QCI1), service stream 2 (QCI1)}, statistical multiplexing bundle 2; {service stream 3 (QCI2)}, statistical multiplexing bundle 3 {service stream 4 (QCI3)} and statistical multiplexing bundle 4 {service stream 5 (QCI4)} and their respective ABBRsbundle (ABBRs of the statistical multiplexing bundles), and controls the encoder to perform encoding. Based on the statistical multiplexing bundle 1 {service stream 1 (QCI1), service stream 2 (QCI1)}, statistical multiplexing bundle 2 {service stream 3 (QCI2)}, statistical multiplexing bundle 3 {service stream 4 (QCI3)} and statistical multiplexing bundle 4 {service stream 5 (QCI4)} and their respective ABBRsbundle determined by the eBM-SC, MCE performs resource allocation and allocates services of different bundles to different MCHs.
The signaling structure employed by the method is as follows:
Session start{Bundle ID list {ABBRbundle {TMGI list}}}Session update{Bundle ID list {ABBRbundle {TMGI list}}}
A study has found that the output of the joint encoded multiplexing stream of services with the same QCI is similar to a Constant Bit Rate (CBR) service. FIG. 3 is a schematic diagram illustrating the relationship between the allocated bit rate and the real-time bit rate of the CBR service. As shown in FIG. 3, a study result shows that the real-time bit rate of CBR is not constant, but with some changes, which however, will further provide a multiplexing gain.
FIG. 4 is a simulation chart illustrating the multiplexing gain of 4 CBR services. As shown in FIG. 4, the multiplexing gain of 4 CBR services may approach 16%. For a 5M bandwidth, it is equivalent to 800 Kbps. The inventor of the present invention has recognized that the multiplexing gain of multiple CBR services is quite considerable.
Hence, the inventor arrives at the following findings:
1. The more services are multiplexed, the higher gain can be achieved.
2. If the Internet Service Provider (ISP) chooses to joint-encode the services with the same QCI, for services with different QCIs, this will produce multiple joint-encoded streams each for one QCI respectively, and multiplexing gain will be produced when these streams are multiplexed together.
Accordingly, there is provided an evolved Multimedia Broadcast Multicast Service system and method for performing statistical multiplexing of services with different QCIs to further increase the system capacity.